beta-carotene (Provitamin A) has recently been shown to be an effective chemotherapeutic agent in the treatment and prevention of cancer. Moreover, carotenes produced biosynthetically (containing 9-cis isomers) appear to be a more effective antitumor agents than those presently manufactured chemically (all-trans isomers). At present, there is no cost competitive process of biosynthetically producing beta-carotene. We have identified a microalgal species which can be grown under conventional, clean-room, fermentation conditions, and produces a mixture of beta- carotene and gamma-carotene. The gaol of this research project is to produce a pharmaceutical grade beta-carotene under aseptic conditions at a cost competitive with the chemical synthesis route. In Phase I, we shall begin the optimization of the beta-carotene productivity of this microorganism through improvements to the medium composition and the physical parameters of the fermentation. We shall also screen for overproducing clone lines which may have a deregulated biosynthetic pathway. On the basis of these preliminary results we will be able to determine the economic feasibility of the overall approach. During Phase II, the optimization and scale-up development will continue in preparation to establishing a commercial scale process.